You could use a CAT4101 based driver and simply add a few more red leds to make up for the difference in forward voltages. The Cat4101 is rated to drive strings of leds up to 25 volts. With that knowledge, you could drive 6-7 "white", "cyan" or "violet leds per string. The "red" would require at least 8 per string to keep all the Cat4101's happy with a low voltage drop.
You could power your lighting system with a Meanwell 24 volt 6.5 amp supply. They're available for cheap on FleaBay.

That's true and that circuit would be a heck of a lot simpler. I have seen your work with the Cat4101, and it seems easy enough to follow. Especially with all the circuit diagrams and parts lists you have been nice enough to share, O2surplus. Thank you for that.

The only problem I have is the filler colors can really crowd out the white if they're not used very sparingly. I could maybe go as high as two of each filler per side, but any more would be pushing it. Could you substitute a high wattage resistor for the additional LEDs to even out the voltage?